NCI Dictionary of Genetics Terms

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Welcome to the NCI Dictionary of Genetics Terms, which contains technical definitions for more than 150 terms related to genetics. These definitions were developed by the PDQ® Cancer Genetics Editorial Board to support the evidence-based, peer-reviewed PDQ cancer genetics information summaries.

12 results found for: F
facies
(FAY-sheez)
A distinctive facial feature or expression that is characteristic of a specific condition.
false-positive result
(… PAH-zih-tiv reh-ZULT)
A test result that indicates an individual is affected and/or has a certain gene mutation when he or she is actually unaffected and/or does not have the mutation; i.e., a positive test result in a truly unaffected or mutation-negative individual.
familial
(fuh-MIH-lee-ul)
A phenotype or trait that occurs with greater frequency in a given family than in the general population; familial traits may have a genetic and/or nongenetic etiology.
family history
(FA-mih-lee HIH-stuh-ree)
The genetic relationships within a family combined with the medical history of individual family members. When represented in diagram form using standardized symbols and terminology, it is usually referred to as a pedigree or family tree. Also called family medical history.
family medical history
(FA-mih-lee MEH-dih-kul HIH-stuh-ree)
The genetic relationships within a family combined with the medical history of individual family members. When represented in diagram form using standardized symbols and terminology, it is usually referred to as a pedigree or family tree. Also called family history.
FDR
The parents, siblings, or children of an individual. Also called first-degree relative.
fibrofolliculoma
(FY-broh-fuh-LIH-kyoo-LOH-muh)
A benign tumor of the hair follicle that appears as a small, whitish papule. Fibrofolliculomas are typically found on the face, ears, neck, and upper torso. They are pathognomonic for Birt-Hogg-Dubé syndrome, a hereditary condition associated with the development of kidney cancer.
first-degree relative
(first-deh-GREE REH-luh-tiv)
The parents, siblings, or children of an individual. Also called FDR.
FISH
A technique used to identify the presence of specific chromosomes or chromosomal regions through hybridization (attachment) of fluorescently-labeled DNA probes to denatured chromosomal DNA. Examination through a microscope under fluorescent lighting detects the presence of the colored hybridized signal (and hence presence of the chromosome material) or absence of the hybridized signal (and hence absence of the chromosome material). Also called fluorescence in situ hybridization.
fluorescence in situ hybridization
(floor-EH-sents in SY-too HY-brih-dih-ZAY-shun)
A technique used to identify the presence of specific chromosomes or chromosomal regions through hybridization (attachment) of fluorescently-labeled DNA probes to denatured chromosomal DNA. Examination through a microscope under fluorescent lighting detects the presence of the colored hybridized signal (and hence presence of the chromosome material) or absence of the hybridized signal (and hence absence of the chromosome material). Also called FISH.
founder mutation
(FOWN-der myoo-TAY-shun)
A gene mutation observed with high frequency in a group that is or was geographically or culturally isolated, in which one or more of the ancestors was a carrier of the mutant gene. This phenomenon is often called a founder effect.
frameshift mutation
(FRAYM-shift myoo-TAY-shun)
An insertion or deletion involving a number of base pairs that is not a multiple of three, which consequently disrupts the triplet reading frame of a DNA sequence. Such mutations usually lead to the creation of a premature termination (stop) codon, and result in a truncated (shorter-than-normal) protein product.